Process of producing ammonium fluorids.



- and fluorid of ammonium 'monia is cause UNITE STATES PATENT oFFioE.

Hownnn r. CHAIPPELL, or NEW YORK, N. Y., ASSIGNOR ro MIlZNERAL rnonuc'rs con- IORATION, OF NEW YORK, N. Y.,' A. CORPORATION OF MAINE.

PROCESS OF PRODUCING AMMONIUM FLUOBIDS.

No Drawing.

To all whom it may concern:

Be it known that I, HOWARD F. CHAPPELL, a citizen of the United States, residing in the borough of Manhattan, city, county, and State of New York, have invented certain new and useful Improvements in Processes of Producing Ammonium Fluorids; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to a cheap and efiicient method of producing acid fluorid of ammonium (ammonium bi-fluorid) from the gases evolved when phosphate rock, apatite, bones or other phosphatic materials containingfluorin compounds are decomposed by sulfuric or other acids in the process of making phosphoric acid or superphosphates. This process is based upon the discovery that when these gases which contain hydrofluoric acid andsilicon fluorid, are sub ected to the action of ammonia, ammonium bifluorid and ammonium fluorid are produced, with the formation of silica or hydrate of silica which is precipitated, The gases generated in the mixing chamber by the action of acids on phosphates containing fluorids are drawn into towers of suitable construction down which a spray of aqueous amd to fall. The liquid containing the precipitated silica is drawn off at the bottom of the tower, moved therefrom by filtration orother suitable methods and the clarified solution which'contains ammonium fluorid and ammonium bi-fluo'rid may be commercially utilized withou further purification, or the fluorids may be recovered in a purified form from the liquid by distillation, or otherwise.

Water may be substituted in place of ammonia, for absorbing the gases generated when phosphatic materials containing fluorin compounds are' sub ected to the action of acids, thereby forming a solution containing hydrofluoric acid and hydrofluosilicic Specification of Letters Patent. I Application filed July 17, 1913. Serial No. 779,506.

1 monium will be the silica re- I Patented Aug. '7, 1917.

'acid. By introducing ammonia into the water which has absorbed these gases, silica will be precipitated and fluorids of amformed. The fluorids of ammonium will remain in solution and may be recovered in a purified form by distilla-v tion and crystallization or otherwise.

When recovering ammonium bi-fluorid and ammonium fluorid through the absorption of fumes from acid phosphate mixers by use of a series of two or more towers, by spraying each tower with the filtered liquor from the following tower in the series, it is possible to obtain a much more concentrated solution of ammonium bifiuorid with a minimum loss of ammonia.

Having described my invention what I claim is: a

1. The process of producing ammonium bi-fluorid and ammonium fluorid, which comprises absorbing in ammonia the fluorin present in the gases evolved in the production of phosphoric acid and phosphates from phosphatic material containing fluorin; substantially as described.

2. The process of producing ammonium bi-fiuorid and ammonium fluorid, which comprises subjecting action of ammonia in removing the resulting silica, ing the fluorids of ammonium; as described.

3. The process of producing ammonium bi-fluorid and ammonium fluorid which comprises adding ammonia to an aqueous solution containing silicon fluorid, removing the presence of water,

and recoverthe separated silica and recovering the am-' monium bi-fluorid and ammonium fluorid; substantially as described.

.4. The process of producing ammonium bi-fluorid and ammonium fluorid, which comprises passing the gases and vapors containing silicon fluorid derived from the treatment of phosphatic material containing silicon and fluorin, into contact with an aqueous liquor containing ammonia, separating'the liquid, after having been brought into'contact one'or more times with the said silicon fluorid to the substantially gases and vapors, from precipitated silicon In testimony whereof I afiix my signature, clompounds, gnil thgreafter again brillllgillllg 'in' presence of two witnesses. t e so-treate iqui into contact Wit t e l gases andfvapors, thereby obtaining a cor- H W CHAPPELL' 5 r'espondingly concentrated solution with a Witnesses: minim-um loss of ammonia; substantially as M. A. BILL,'

described. M. L. BOWEN. 

